1. Field of the Invention
The present invention relates to a centrifugal blower. More particularly, the present invention relates to a centrifugal blower having an anti-leakage element.
2. Description of Related Art
A blower is a machine capable of generating a differential pressure to force air to flow. A common axial fan blows an air flowing in a direction substantially parallel to a rotation axis of the axial fan. A centrifugal blower blows an air flowing in a direction substantially perpendicular to a rotation axis of the centrifugal blower.
FIG. 1A is a schematic perspective view of a conventional centrifugal blower, FIG. 1B is a schematic top view of the centrifugal blower of FIG. 1A, and FIG. 1C is a schematic cross-sectional view of the centrifugal blower of FIG. 1B taken along a line I-I′. Referring to FIGS. 1A, 1B, and 1C, the conventional centrifugal blower 100 includes a casing 110, a motor 120, and a fan structure 130. The casing 110 has a top portion 112, a bottom portion 114, and a side wall 116. The top portion 112 has an inlet 112a. A side 116b of the top portion 112 and a side 116c of the bottom portion 114 extend and are engaged together to form a side wall 116. The side wall 116 is connected to the top portion 112 and the bottom portion 114 respectively, and has an outlet 116a. 
The motor 120 is fixed in the casing 110. The fan structure 130 is disposed in the casing 110. The fan structure 130 has a body 132 and a plurality of blades 134. The body 132 is connected to the motor 120, and the blades 134 surround the body 132 and are connected to the body 132. The fan structure 130 driven by the motor 120 rotates about an axis 10 in a rotation direction 20.
When the centrifugal blower 100 operates, the rotating fan structure 130 sucks in air via the inlet 112a and blows out the air via the outlet 116a. In specific, before entering the blades 134 via the inlet 112a, the air flows in a direction substantially parallel to the axis 10. After the air is pressurized by the blades 134, the air passes through an increased pressure flow chamber or a volute chamber 30 located between the blades 134 and the side wall 116, and moves away from the casing 110 via the outlet 116a in a direction substantially perpendicular to the axis 10.
However, the static pressure of the air flowing in the volute chamber 30 is generally greater than the pressure of the air at the inlet 112a, such that the air within the volute chamber 30 leaks through a clearance 40 between the top portion 112 of the casing 110 and each of the blades 134. Therefore, the conventional centrifugal blower 100 has lower operation efficiency.